1. Field of the Invention
The present invention relates to a device for improving intake air noise (intake air tone) caused from an intake air system of a vehicle and the like.
2. Description of the Related Art
An intake air noise adjuster capable of causing a vigorous intake air noise by introducing an intake air noise (caused to an intake air passage to an engine) in a vehicle compartment during traveling is conventionally known.
Japanese Patent Application Laid-Open No. 2005-139982 (=JP2005139982) discloses an intake air noise adjuster (referred to as “tone quality control device”) including a communicating conduit, an elastic body and an additional conduit.
On an outer periphery of an intake air duct, the communicating conduit is mounted in a position further away from an engine than a position where a throttle chamber 8 for increasing and decreasing intake air amount of the engine is disposed. As such, the communicating conduit communicates with the intake air duct.
The elastic body blocks the communicating conduit, and vibrates according to an intake air pulsation in the intake air duct.
The additional conduit has a first open end connected to the communicating conduit and a second open end open to an external air.
In the conventional intake air noise adjuster, the elastic body vibrates according to the intake air pulsation caused in a gas in the intake air duct. As such, the intake air noise is radiated outwardly to the external air from the second open end of the additional conduit, thus introducing a rigorous intake air noise into the vehicle compartment.
With the related intake air noise adjuster of JP2005139982, irrespective of driver's depressing of an accelerator pedal, the intake air noise is increased according to the intake air pulsation caused in the gas in the intake air duct.
Therefore, the intake air noise is unintentionally increased even in the following states for securing silence: relaxed acceleration, idling and the like when the driver's depressing of the accelerator pedal is small.